Cadmium (Cd(ll)) is a common, highly toxic environmental contaminant and a component of cigarette smoke. While the cellular effects of Cd(ll), DNA damage and oxidative stress, are well established, their origins remain unclear. Two hypotheses have been proposed to explain Cd(ll) toxicity. Cd(ll) may generally displace Zn(ll) and Fe(ll) from metalloproteins, with these liberated metal ions resulting in the observed damage. Alternately, Cd(ll) may bind and inhibit specific proteins involved in the cellular responses to DNA damage and oxidative stress. The goal of this project is to examine these hypotheses and further our understanding of Cd(ll) toxicity. High-throughput techniques for isolating proteins and determining their in vivo Cd(ll) binding will be used to examine Cd(ll) binding by target proteins in vivo. The in vitro Cd(ll) binding and metal specificity of such proteins will be evaluated to provide a biochemical understanding of how Cd(ll) targets specific proteins. Finally, we will employ X-ray absorbtion microbe techniques to examine the effects of Cd(ll) on the cellular distribution of biologically important metals. Together this approach will provide detailed biochemical information regarding the cellular origins of Cd(ll) toxicity. [unreadable] [unreadable]